Process of removing pyridine from nitrocellulosic materials



and the pyridine.

Patented Dec. 8, i925.

UITE STATES LEON w. EBEBLIN, or moans/run, new YORK, .ASSIGNOR To EASTMAN KODAK com PANY, or noon'ns'rnn, new YORK, A CORPORATION oF'NEw YORK.

PROCESS OF REMOVING PYBIDINE FROM NITROCELLULOSIC MATERIALS.

No Drawing. Application filed February To all whom it may concern: 7

Be it known that I, LEON W. EBERLIN, a

citizen of the United States of America, re-

siding at Rochester, in the county of Monroe and State ofNew York, have invented certain new and useful Improvements in Processes of Removing Pyridine from Nitrocellulosic Materials, of which the following is a full, clear, and exact specification.

This invention relates to processes of removing pyridine from cellulosic materials which are impregnated therewith. One object of the invention is to provide a process for removing pyridine from these materials, such as solid colloidized nitrocellulose, for example, in a rapid, thorough andrelatively inexpensive manner. Other ob ects Wlll hereinafter appear.

In reducing the viscosity characteristics of nitrocellulose, especially solid colloidized nitrocellulose, such as pyroxylin waste and film scrap, it has been proposed to use solutions of pyridine which thoroughly impregn ate the material. Even though the latter 1s in a solid condition it is sufficiently softened so that the pyridine enters the interior there of. Pyridine has an odor which is ob ectionable to many people, and even small traces of it give off a detectable smell. Moreover, any considerable amounts of it in nitrocellulose tend to bring about a molecular transformation which may proceed too far. It is, therefore, highly deslrable to provide a rapid, simple and inex ensive process for eliminating this materia from the treated nitrocellulose. While I have referred particularly to the removal of pyridine from solid colloidized nitrocellulose, the method is equally applicable to any material, especially cellulosic material, of an analogous nature.

I have found that p ridine may be successfully removed by subjecting the material containing it to.a chlorinating agent. I rei'er to have present also a penetrant, W ich facilitates the action between the chlorine While various chlorinating agents may be employed, 1 find that the simplest one is chlorine gas itself. As a penetrant I may employ a solvent properly toned by a diluent so that it does not dissolve the material but merely softens'the latter to permit the action to take place. In the case of nitrocellulose a 20% aqueous solution of a usual solvent, such as acetone or 11, 1925. Serial No. 8,575.

methyl alcohol or methyl acetate, is useful. But the proportion can be varied through a considerable range, provided the nitrocellulosic material is not dissolved or rendered so gunnny as to stick together into an unmanageable mass. v

lVhile the action may be facilitated or speeded up by the use of heat, this is unnecessary, as useful rapidity is obtained at room temperature. The process is, of course, conducted in a vessel which is practically proof against the action of chlorine.

While I shall now describe one form of my invention by way of example, it will be,

.nnderstood that the invention is not restricted to the details of this illustration except as indlcated in the appended claims. Nitrocellosic material, especially one containing solid 1 colloidized nitrocellulose, associated or not with high-boiling compounds like camphor and butyl alcohol, such as pyroxylin waste or film scrap, which has been impregnated with pyridine in previous operations, is immersed in a loath comprising a 20% aqueous solution of acetone. After the penetrant, acetone, has been allowed to act on the material to slightly swell the latter, chlorine gas is bubbled up through the liquid in intimate contact with the material until there is a dis: tinct odor of chlorine when the gas supply is shut oii.

The film is then left in the chlorinated hath until a test shows that the pyridine has been. sufficiently decomposed into harmlessand readily removable substances. The time of this treatment is, of course, variable and depends upon the concentration of pyridine in the material, the extent to which the material has been comminuated before the treatment, and upon the strength of the penetrant, as well as the tern erature. Working at room temperature wlth comminuted film scrap the action is sufliciently complete in about 30 minutes.

When the action is finished, the chlorinating bath is drained from the material and the latter washed in several changes of water. lit is then treated,- say by immersion,

in an anti-chlor solution. The simplest and I most inexpensive bath of this nature is one 3 of sodium thiosulfate, say a 5 to 10% aque o'us solution.

This acts very quickly. Finall the ma.- terial is washed to removethe t iosulfat'e. This can be done continuously incold running water or by treatment in successive cellulosic vmaterial which is impregnated with the same, which comprises treating said material with a chlorinating agent to decompose the pyridine and then treating the material with an anti-chlor solution.-

2. The process of removing pyridine from .cellulosic material impregnated with the same, which comprises treating said material with a chlorinating agent in the presence of a penetrant to decompose the pyridine and treating the material with an anti-chlor solution. I

3. The process of removing pyridine from solid colloidized nitrocellulose containing the same, which 'comprises treating the said nitrocellulose. with a chlorinating'agent in the presence of a mixture of water and a penetrant until the pyridine is substantialk ly decomposed, removing the nitrocellulose from themixture and treating the same with an anti-chlor solution until any free chlorine is neutralized.

4. The pro'cessof removing pyridine from solid colloidizednitrocellulose containing the same, which comprisestreating the same with a chlorinating agent in the presence of a penetrant until the pyridine is substantially decomposed, thereafter treating the nitrocellulose with an anti-chlor solution to remove any free chlorine and finally washing the nitrocellulose to remove the com-.-

pounds formed by the previous steps.

5. The process of removingpyridine from solid colloidized nitrocellulose containing the same, which comprises immersing said nitrocellulose in an aqueous bath containing suflicient nitrocellulose solvent to. act

as a. penetrant without dissolving said nitrocellulose, bringing chlorine gas into contact with said nitrocellulose while thus immersed, allowing the chlorine to decompose the pyridine, separating the nitrocellulose from said bath, treating it with an anti-.chlor solution to neutralize anyjfree chlorine remaining therein, and final] washing the nitrocellulose to thorough y remove the compounds formed in the previous steps.

6. The rocess of removing pyridine from nitrocellu ose film scrap'containing-the same, which comprises immersing said scrap, while in small pieces, in a 20% a ueoussolution' of a nitrocellulose solvent,bu bling chlorine gas throu h said solution until there isva distinct odor of chlorine when the gas supply ,is shut ofi, allowing the chlorine bath to complete the decomposition of the pyridine in the scrap, draining the'bath from the scrap, rinsing the same, and then immersing it in a bath of thiosulfate of an alkali metal until any remaining chlorine i same, which comprises immersing said scrap in a 20% aqueous solutlon of acetone and nitrocellulose film scrap containing the,

permitting the scrap to swell slightly, bubbling chlorine gas through the bath into contact with the scrap, until a distinct odor of chlorine remains when the gas supply is shut off, allowing said chlorine in the bath to complete the decomposition of the pyridine in the scrap, draining the bath "from the scrap and washing the latter in water, immersing the scra in a bath of sodium thiosulfate to neutra ize any remaining chlorine, and finally washing the scrap with water until the compounds introduced by the previous steps are moved. I Signed at Rochester, New York, this 5th day of February 1925. y

I LEON W. 'EBERLIN;

. substantially re- 

